Area Code Atlas

NPA 503 assigned to Oregon

In 1947, area code 503 was assigned as one of the original North American area codes, covering the entire state of Oregon.

NANP-SPLIT OF 503 (OREGON) NUMBERING PLAN AREA (NPA)

NPA 503 split to create 541

Area code 503 was split in November 1995, with most of Oregon outside the northwest corner receiving the new area code 541, to address number exhaustion and geographic division, limiting 503 to northwestern Oregon including Portland.

Permissive 10-digit dialing begins for 503/971 overlay

Permissive 10-digit dialing began on July 11, 1999, for calls within and between the 503 and 971 area codes in northwestern Oregon, allowing callers to use either 7 or 10 digits during the transition to the overlay.

Concentrated Overlay of 503 (Oregon) NPA with 971 NPA

971 overlay relief plan announced for 503

The Oregon Public Utility Commission approved a concentrated overlay of area code 503 with new area code 971, excluding 14 rate centers in coastal counties. The plan was announced on July 21, 1999, to address number exhaustion in northwestern Oregon.

Permissive Dialing Extended for the 503 / 971 Concentrated Overlay (Oregon)

NPA 971 overlay activated for 503

Area code 971 was activated as an overlay for most of the 503 area on October 1, 2000, addressing number exhaustion in the Portland metropolitan area and surrounding communities. The overlay initially excluded Clatsop and Tillamook counties, requiring ten-digit dialing for calls within and between the 503 and 971 NPAs.

Mandatory 10-digit dialing for 503/971 overlay

Mandatory 10-digit dialing was implemented for all calls within and between the 503 and 971 NPAs on October 1, 2000, following the end of the permissive dialing period.

Expansion of Concentrated NPA 971 Overlay with NPA 503 (Oregon)

Permissive 10-digit dialing for overlay expansion to Clatsop and Tillamook counties

A permissive dialing period for 10-digit dialing began on October 21, 2007, in preparation for the expansion of the 503/971 overlay to include Clatsop and Tillamook counties.

971 overlay expanded to Clatsop and Tillamook counties

On April 27, 2008, the area code 971 overlay was expanded to include Clatsop and Tillamook counties, completing the overlay coverage for the entire 503 region.

Mandatory 10-digit dialing for overlay expansion to Clatsop and Tillamook counties

Mandatory 10-digit dialing began on April 27, 2008, as the 503/971 overlay was expanded to include Clatsop and Tillamook counties. This marked the full implementation of the overlay in all of northwestern Oregon.

Overlay of 503 with 971 in Oregon

An overlay complex was implemented in April 2008, adding area code 971 to the northwest Oregon region originally served by 503, including Clatsop and Tillamook counties, requiring ten-digit dialing.

Clatsop and Tillamook counties added to 971 overlay

Clatsop and Tillamook counties were added to the 971 overlay on April 27, 2008, expanding the overlay to cover the entire 503 numbering plan area.